Thermal/Acoustical Liner

ABSTRACT

A multi-layer liner material for use as a thermal and acoustical insulator which is lightweight, breathable, hydrophobic, oleophobic and fire-resistant. A central insulation core layer is contacted on a first surface by a first highly breathable layer and on a second surface by a second highly breathable layer, such that these three layers are resistant to water or oil penetrating the insulation core layer causing the liner to gain weight. The first and second highly breathable layers are preferably made from inherently flame resistant fibers and treated with a fluorocarbon surface treatment for water repellency, UV resistance and mold/mildew resistance. The first highly breathable layer is adjacent a facing layer while the second highly breathable layer is adjacent a backing layer. At least one surface of one of the first or second highly breathable layers, or facing or backing layers may include a carbon printing pattern to provide ESD protection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/714,400 titled “Thermal/Acoustical Liner” filed Sep. 25,2017 which is a continuation-in-part of U.S. patent application Ser. No.14/186,355 titled Thermal/Acoustical Liner filed Feb. 21, 2014 andclaims priority from U.S. Provisional Patent Application No. 61/767,443entitled “Thermal/Acoustical Liner For Cargo Aircraft”, filed on Feb.21, 2013 all of which are incorporated fully herein by reference.

TECHNICAL FIELD

The present invention relates to a thermal acoustical liner for use, forexample, in aircraft and other similar environments.

BACKGROUND INFORMATION

Current thermal acoustical liners, for example those used in aircraft,suffer from various performance issues. The liners tend to trap moistureand contaminants, such as water, oil, sand, dust and pollutants againstthe air frame of the aircraft. These liners are not breathable/airpermeable and this leads to accelerated corrosion damage.

The liners currently used also add more weight to the aircraft thanshould be required in order to deliver the necessary sound deadening andthermal insulation performance requirements. For example, the build outof an existing liner (in terms of weight/square yard) is as follows: theface fabric is 14-18 oz/yard (PVC coated polyester), the microlitefiberlite AA insulation is 0.60 lb/cu. ft. or approximately 7.2 oz./sq.yd, a 1.0 oz vinyl barrier, a 2.0 oz. backing fabric, and an additional2.0 oz due to the quilting process result in a total (not includingattachment means) of 26-30 oz. total dry weight per square yard, orroughly 163-188 lbs per 100 sq. yards (typical aircraft application . .. such as a Chinook helicopter).

Additionally, the existing liners absorb moisture and hydrocarboncontaminants in the field, which adds significant additional weight tothe aircraft when in use, as much as 50% or 81-94 lbs. per 100 sq.yards. Additionally, the thermal and acoustical performance of currentliners is limited due to limitations of fiberglass insulation and thequilting assembly that is required, compressing the insulation anddegrading its thermal and acoustic properties. Additionally, thefiberglass insulation fibers breakdown/degrade due to vibration(breakdown and compression of fiberglass) and absorption of moisture andoil/fuel contaminates. As the liner becomes contaminated with dust,lubricants, fuel, hydraulic fluid, a fire hazard can be created.

In addition, prior art liners utilizing fiberglass core layers aresusceptible to water infiltration and thus trapping water in thefiberglass material, and further to the fiberglass material droppingwhen installed on a vertical surface.

Accordingly, what is needed is a thermal acoustical liner material thatdoes not trap moisture or contaminates, that allows forbreathability/air permeation to prevent corrosion due to trappedmoisture/condensation against the air frame, which is lightweight, whichhas improved thermal and acoustical performance, which can dissipatestatic charges rapidly, and which reduces the fire hazard.

SUMMARY OF THE INVENTION

The present invention features a multi-layer liner that comprises a highperformance, Fire Resistant (FR), nonwoven, amorphous thermoplasticpolyetherimide, (PEI) resin (or equivalent), or foam insulation corelayer with an upper surface and a lower surface; a first, high strength(high tear, tensile, and abrasion performance) highly breathable layerlocated on the upper surface of the insulation core layer, the firsthighly breathable, waterproof, filter layer constructed from an ePTFEmembrane or equivalent; a second highly breathable layer located on thelower surface of the insulation core layer, the second highlybreathable, waterproof, filter layer constructed from an ePTFE membraneor equivalent; a facing layer located on the first highly breathablelayer, wherein the facing is constructed from a material that isfire-resistant; and a backing layer located on the second highlybreathable later, wherein the backing is a highly breathable,fire-resistant rated material, wherein the layers of the liner areconnected to one another with an adhesive lamination process. In thepreferred embodiment, at least one of the facing layer and the backinglayer is treated with an appropriate nanoscopic coating to provide thewaterproof characteristics desired.

The entire thermal acoustical liner system dissipates static chargesthrough the use of an electrostatic dissipative carbon printed on theinside of one or more of either or both of the face and backing layersof the lamination. The system is assembled by laminating or adhering thelayers together in a 3 dimensional blanket or acoustical and thermalliner that is not compressed or punctured. The entire liner system isapproximately 30% lighter than the existing design and does not gainsignificant weight in use.

It is important to note that the present invention is not intended to belimited to a system or method which must satisfy one or more of anystated objects or features of the invention. It is also important tonote that the present invention is not limited to the preferred,exemplary, or primary embodiment(s) described herein. Modifications andsubstitutions by one of ordinary skill in the art are considered to bewithin the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reading the following detailed description, takentogether with the drawings wherein:

FIG. 1 is a detailed cross-sectional view of the multi-layer lineraccording to one embodiment of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention features a thermal acoustical liner 10, FIG. 1,which is breathable, hydrophobic, oleophobic and fire-resistant. Theliner is intended for use in a cargo aircraft on the interior airframeof the aircraft to help deaden acoustical noise coming from theairframe, although other uses are contemplated and within the scope ofthe present invention. The liner includes multiple layers, which arelaminated to one another.

The acoustical liner 10 includes a facing layer 12 that is highlybreathable and fire-resistant rated. The facing layer faces the interior(passenger and/or cargo) region of the aircraft. The facing layer 12provides a surface oil resistance preventing the ingress of oils andother contaminants with surface tensions greater or above 21 dynes/cmand hydrophobic resistance (resistant to water absorption). The facing12 is preferably a combination of rayon, nylon and aramid/para-aramidwoven fabric which has high strength and durability and light weight. Inan alternative embodiment the facing 12 uses woven knitted or nonwovenmaterials made from inherently flame and/or fire resistant withoutchemical treatment and/or thermally stable materials.

The facing 12 may also be treated with a fluorocarbon surface treatmentfor water repellency, UV resistance and mold/mildew resistance. Analternative embodiment uses woven, knitted or nonwoven materials thatare inherently flame retardant materials or by their polymer make-up donot support combustion. Such materials can be aramid/para-aramid,polyimide, polyamidimide, fluoropolymer, melamine, glass and any otherknown fabric material that does not support combustion. Further thematerials shall not be treated with flame retardant treatments whichgive off potentially toxic or harmful vapors upon combustion or thermaldegradation. Examples of toxic or harmful vapors, their maximumallowable concentrations and the test results of the invention arelisted in Table I.

The facing 12 is in contact with a first highly breathable layer 14. Thefirst highly breathable layer 14 is preferably an ePTFE membrane. Beingmade from ePTFE is desirable in that the material of the first highlybreathable layer 14 is thermally stable and inherently flame retardantwhich therefore adds to the overall inherent flame resistance of the 5layer design. The ePTFE material exhibits an air permeability of 0.10CFM to allow moisture vapor to pass through the 5 layer design at a rateof 3500 g/m²/24 hr or greater, while maintaining a resistance to waterentry pressure of at least a 10 m water column and also blocking orpreventing the insulation core layer 16 from retaining water and oil, aswell as sand/dust and other contaminates down to 0.3 microns. Theconcept is not limited to ePTFE films but may also utilize any airpermeable layer offering water repellency performance made frompolyurethane or polyolefin.

An insulation core layer 16 contacts the first highly breathable layer14. The insulation core layer 16 is breathable, hydrophobic andfire-resistant. In one embodiment, the insulation core layer 16 ispreferably a nonwoven polyetherimide (Ultem) Resin blended layer that ishighly air permeable, hydrophobic and oleophobic and which providesimproved core thermal and acoustical performance characteristics vs.existing fiberglass cores.

Preferably the insulation core layer will be constructed with acombination of fibers of one or more deniers such that it providessufficient bulk to provide the desired thermal insulation and sufficientsurface area and volume to provide the desired sound attenuationproperties. In addition to the attributes above, a nonwoven material ispreferred for its flexibility and stability to vibration. It isdesirable to use a flexible material so that the multi-layer liner caneasily be removed, either fully or partially, while the aircraft, orvehicle, is in flight to inspect behind the liner.

Ultem Resins are a group of amorphous thermoplastic polyetherimide (PEI)resins with elevated thermal resistance, high strength and stiffness,and broad chemical resistance. The insulation core layer 16 passes allrequired fire-resistance and smoke requirements. In an alternativeembodiment the insulation core layer 16 uses woven, knitted or non-wovenmaterials that are inherently flame retardant materials without chemicaltreatment or by their polymer make up do not support combustion (againwithout chemical treatment) and do not give off any of a plurality ofknown toxic or harmful vapors upon combustion or thermal degradationsuch as an amorphous polysilicic acid drawn from SiO2 material, such asBelchem fiber, or oxidized polyacrylonitrile, such as CarbonX or similarinherently flame retardant materials. Materials chosen must be durableto vibrational integrity testing MIL-STD-810G method 514.6, Procedure Iwithout needing to be quilted or other means for preventing fibermigration.

In another embodiment, the breathable, hydrophobic and fire-resistantinsulation core layer 16 is an open-cell foam, providing goodbreathability, inherent fire-resistance, and may be treated to behydrophobic and oleophobic. Such a foam material possesses improvedthermal and acoustical properties compared to existing fiberglass corematerials. For example, a typical fiberglass batting has a density of0.60 pounds per cubic foot and a thermal conductivity of 0.25(Btu·In.)/(Sq.Ft·Hr° F.). One foam material usable in connection withthe present invention is a hydrophobic melamine foam capable of passingFederal Aviation Administration flammability, smoke generation, andcombustion toxicity requirements, with a density of less than or equalto 0.60 pounds per cubic foot and a thermal conductivity of greater thanor equal to 0.24 (Btu·In.)/(Sq.Ft·Hr° F.), and a second similar melaminefoam with a density of less than 0.40 pounds per cubic foot and athermal conductivity of 0.26 (Btu·In.)/(Sq.Ft·Hr° F.). These foams areavailable from Polymer Technologies, Inc. of Newark, Del.

Another such foam for use in the present invention is a polyimide foamwith a density of less than 0.40 pounds per cubic foot and a thermalconductivity of 0.34 (Btu·In.)/(Sq.Ft·Hr° F.). This foam also hasinherent fire-resistant properties, passing standard Federal AviationAdministration flammability, smoke generation, and combustion toxicityrequirements. This foam is available from Boyd Corporation ofPleasanton, Calif.

The three examples of foam listed all have excellent long-term stabilityand are resistant to vibration and temperature changes common inaerospace applications. Additionally for the three examples of foam, fora given weight of foam, the insulation value will be greater or for agiven insulation value the weight of foam will be less when compared tothat of the fiberglass example cited above and are not subject to thefiberglass insulation “dropping” when installed on a vertical surface orbecoming less effective due to moisture. In this way, these foams allhave improved thermal efficiency, or unit of thermal insulation per unitof mass, when compared to fiberglass insulation products. As mentionedabove, the noted and equivalent foams will exhibit improved acousticalenergy absorption compared to the prior art fiberglass insulation ofsimilar thickness, thus making the aircraft interior quieter compared tothe prior art fiberglass insulation.

In yet another embodiment, the insulation core layer 16 includes the useof a non-woven aramid/para-aramid fiber core (such as Dupont Kevlar®,replacing the Ultem, to provide both the thermal and acousticalcharacteristics required, the light weight characteristic and theability of the liner to provide “ballistic or shrapnel protection” forthe sides of the aircraft.

The insulation core layer 16 contacts a second highly breathable layer18. The second highly breathable layer 18 is preferably an ePTFEmembrane. Being made from ePTFE is desirable in that the material of thesecond highly breathable layer 18 is thermally stable and inherentlyflame retardant which therefore adds to the overall inherent flameresistance of the 5 layer design. The ePTFE material exhibits an airpermeability of 0.10 CFM to allow moisture vapor to pass through thefive layer design at a rate of 3500 g/m²/24 hr, while maintaining aresistance to water entry pressure of at least a 10 m water column andalso blocking or preventing the insulation core layer 16 from retainingwater and oil, as well as contaminates down to 0.3 microns. The conceptis not limited to ePTFE films but may also utilize any air permeablelayer offering water repellency performance made from polyurethane orpolyolefin. Further the materials shall not be treated with flameretardant treatments which could give off potentially toxic or harmfulvapors upon combustion or thermal degradation. Examples of toxic orharmful vapors, their maximum allowable concentrations and the testresults of the invention are listed in Table I.

The second highly breathable layer 18 contacts a backing layer 20, whichis designed to face or contact the airframe of an aircraft. The backing20 is a highly breathable, fire-resistant rated material. The backing 20is preferably combination of rayon, nylon and aramid/para-aramid knittedfabric. In an alternative embodiment the backing layer 20 uses woven,knitted or nonwoven materials made from inherently flame resistant orthermally stable materials. The backing 20 may also be treated with afluorocarbon surface treatment for water repellency, UV resistance andmold/mildew resistance. The backing layer 20 provides a surface oilresistance preventing the ingress of oils and other contaminants withsurface tensions greater or above 21 dynes/cm along with hydrophobicresistance (resistant to water absorption). The backing layer 20 thusprovides resistance to oil and water resistance while the overall 5layer design provides resistance to water entry pressures greater than10 m of water and a surface oil resistance preventing the ingress ofoils and other contaminants with surface tensions greater or above 21dynes/cm.

In an alternative embodiment, the backing layer 20 uses woven, knittedor nonwoven materials that are inherently flame retardant materials orby their polymer make up do not support combustion. Such materials canbe aramid/para-aramid, polyimide, polyamidimide, fluoropolymer,melamine, glass and any other known fabric material that does notsupport combustion. Further the materials shall not be treated withflame retardant treatments which could give off potentially toxic orharmful vapors upon combustion or thermal degradation. Examples of toxicor harmful vapors, their maximum allowable concentrations per testmethod BSS 7239 are listed in Table I. The test results of the overall5-layer design are listed in Table I. The test results of the inventionare shown under the right-hand “Liner Material Results” column.

TABLE I Maximum Allowable Liner Material Compound (ppm) Results CO 3,500<10.0 HF 200 <0.5 HCl 500 <1.0 HCN 150 <0.5 SO₂ 100 <1.0 NO/NO₂ 100 <2.0

The multi-layered liner is designed to address all major performancedeficiencies found in prior art liners. Some of the major deficienciesof prior art liners include, but are not limited to; low or no airpermeability and breathability, gaining weight over time through theabsorption of fluids, and electrostatic discharge below “good”performance level. A deficient level of air permeability andbreathability has been found to trap moisture between the thermalacoustical liner and the airframe or vehicle structure leading to anexcessive rate of corrosion. Gaining weight over time is of particularconcern in the field of aviation where increased weight, particularlyweight that is not directly accounted for, leads to issues of fuelconsumption and load capacity which are both potentially dangerous. Evenmore dangerous is the previously flame retardant insulation linermaterial absorbing highly flammable oils and fuels present in anairframe to such an extent that it no longer serves its purpose in theevent of a fire.

The liner 10 will also preferably include electro-static discharge (ESD)performance. For example, preferably 1.0 second or better discharge of a5000 volt charge is achieved using the federal rating and test methodspecified in Federal standard 191A method 5931. In a further preferredembodiment the electro-static discharge will be 0.2 second or better.This level would achieve a classification of “Good” or “Excellent” forstatic dissipative classification using the federal rating and testmethod specified in FTTS-FA-009. In one embodiment, the ESD performanceis achieved by utilizing a carbon impregnated ePTFE in at least one ofthe first and/or second highly breathable layers 14/18. In anotherembodiment, the ESD performance is achieved by using a carbon printingpattern on at least one surface interior of the facing 12 or backing 20as is described in U.S. Pat. No. 9,204,525 B2, or one of the firstand/or second highly breathable layers 14/18. The carbon printingpattern is preferably located on the surface of the facing 12 that comesin contact with the first highly breathable layer 14 or the surface ofthe backing 20 that comes in contact with the second highly breathablelayer 18. In the preferred embodiment, the multi-layer liner provideselectro-static discharge (ESD) performance characteristics in the rangeof 1-100 MOhm when tested with 500 volts potential as per DIN testmethod 54345 or at most a 0.2 second discharge time for 5000 volt chargewhen applied to either the facing or backing as per FED 191A method5931.

The laminated multi-layer thermal/acoustical liner also improves oncorrosion prevention by maintaining a permanent barrier to water and oiland retaining high breathability (air permeability of 0.10 CFM and MVTRof 3500 g/m²/24 hr), thereby assuring that moisture and water does notpenetrate the liner and become trapped against the airframe and theelectronic and hydraulic systems located against the airframe.Preventing water from coming in contact with the airframe reducescorrosion by reducing the water/electrolyte contact with the air-frameand preventing oxidation. Further, the high moisture vapor transportrate ensures that any moisture on the airframe can escape through thematerial. Using the previously mentioned 100 square yards typical for anaircraft application and a value of 3500 g/m²/24 hr it isstraightforward to calculate an overall moisture vapor transmission of292 kilograms or 645 pounds for one aircraft in one period of 24 hours.This leads to a significant reduction in moisture near the airframethereby reducing the rate of corrosion. The liner of the presentinvention is an effective barrier/filter to contaminates (sand, dust,and pollutants like salts and sulfurs) down to 0.3 microns and also doesnot support the growth of mold or mildew. The first and second highlybreathable layers 14/18 of the liner mitigate corrosion. When an ePTFEbarrier membrane is used, the liner is highly breathable and will nothold or trap moisture against the air frame or within the coreinsulation.

The liner of the present invention features improved thermal andacoustical performance. The liner delivers at a minimum an R 1.8insulating value. Prior art liners may have insulation values as high asR1.8 when newly manufactured, but due to mechanical break-down of theinsulation fibers as well as fluid absorption, the insulation value ofprior art liners tends to degrade over time. In this way the presentinvention represents an increase in thermal insulation performance perunit weight. The liner of the present invention also maintains thermalinsulation over time by being resistant to losing the loft or thicknessof the overall product whereas prior art liners have been known todegrade due to vibrational frequencies common in aircraft such ashelicopters. The liner is made resistant to losing loft over timethrough careful selection of the fibers that it is made from, theirmaterial makeup and sizing. Proper sizing of the fibers aids in thethermal insulation and has also been found to be critical to theacoustical performance. Sound attenuation was maximized at a blend of20% 2 denier fibers and 80% 8 denier without sacrificing productstability. The present invention provides acoustical performance of 10%or better across the entire relevant sound wave spectrum, than thecurrently available liners. Anechoic testing has shown the liner toreduce sound transmission across a range of frequencies. Morespecifically it has been shown to reduce sounds in the 250-1,000 Hzrange by 10 dB and sounds in the 1,000 to 10,000 Hz range by 20 dB.Compared to previous technologies this represents an increase inperformance of 30-100%.

TABLE II Transmission Transmission Loss Loss Product 250-1,000 Hz1,000-10,000 Hz Present 10 dB 20 dB Invention Existing  7 dB 10 dBTechnology

Assembly and connection of the layers of the liner is achieved, in oneembodiment, through lamination, not by quilting as is done in prior artliners. Quilting tends to destroy the performance of the liner becausethe quilting process compacts the insulation layer and creates holes inthe surface which allow water and oil to penetrate the liner. When theinsulation is compacted, the insulative value (R value) decreases andits acoustical performance is degraded and the compacted insulation hasan increased tendency to hold water and other contaminates due to themultiple punctures created by quilting. The nonwoven, fire resistant(FR), air permeable, hydrophobic and oleophobic thermal and acousticalinsulation core is constructed at least in part from one or morematerials selected from the group of materials consisting of anon-woven, amorphous thermoplastic polyetherimide (PEI) resin materialor an amorphous polysilicic acid drawn from SiO2 material or oxidizedpolyacrylonitrile or similar that are able to pass vibrational integritytesting MIL-STD-810G method 514.6, Procedure I, without needing quiltingor other means for preventing fiber migration.

In contrast, the present invention uses a lamination process that can beaccomplished using a FR polyurethane (PU) adhesive or via thermalwelding or binding. The lamination process is a four step process thatbuilds up the component layers one at a time by bonding the individuallayers together in a roll/heat/pressure/adhesive based process. Thefinal laminated system is approximated 1 inch thick, or less, withoutinterruptions, punctures or compressions (does not to degradeperformance). The laminated system maintains high breathability/airpermeation characteristics. Lamination also allows for in field repairsdue to the uninterrupted flat surfaces of both the face and backingfabrics. The surfaces allow patch kits with adhesive backings to beapplied and successfully bond providing an effective repair that cannotbe achieved on irregular quilted surfaces. In the embodiment wherein theinsulation layer is foam, the layers may be adhered together using glueor other adhesive.

As a final process the present invention goes through a plasma basedtreatment process to durably apply nano fluorocarbons throughout thepreviously mentioned 5 layer design. This process ensures evenapplication and penetration of all layers. The fluorocarbon treatment isadded to ensure that all layers are hydrophobic as well as oleophobic toresist the penetration or contamination by water and oils. In analternative embodiment each individual layer is treated withfluorocarbons to render each layer oleophobic and hydrophobic. In afurther alternative embodiment the 5 layer design is rendered oleophobicand hydrophobic through a pad bath or dip process application offluorocarbons, or some combination of the aforementioned various methodsof fluorocarbon application as they pertain to each layer or the overall5 layer design. By rendering the liner oleophobic and hydrophobic itwill resist the absorption of fluids and thereby weight gain. Whentesting for weight gain by a one minute soak in water on both facing andbacking layers followed by a 5 minute drip dry the material will gainless than 5% of its original weight. By not absorbing water, it willalso therefore be resistant to the growth of mold and mildew, as themoisture content needed to support growth will not be present in theliner. Test specimens showed no visible evidence of fungal growth whentested according to MIL-STD-810G Method 508.6 84 day exposure, Fungus:Mold culture media (PDA and mineral salts agar).

The liner also features a lower dry weight that the prior art, with theliner preferably reducing the dry weight by 30%. An example of theproduct build out (in weight per square yard) for the multi-layer lineris as follows: a face fabric of 4.0-5.5 oz. nylon (facing layer 12),0.25 oz ePTFE (first highly breathable layer 14), an insulation layer ofUltem nonwoven 1 inch 9.0 oz/sq. yd. (insulation core layer 16), 0.25oz. ePTFE (second highly breathable layer 18), 1.5 oz of backing fabric(backing layer 20), as well as 1.0 oz. added as a result of thelamination and printing processes, for a total (without attachmentmeans) of 16.0-17.5 oz. of total dry weight, or approximately 112.5 lbs.per 100 sq. yards (typical aircraft application . . . such as a Chinookhelicopter). This reduced weight saves approximately 8 oz. per yard overthe prior art liners (the composition and weight of the prior art lineris described in detail in the background). The present inventionprovides for a reduction in dry weight versus the existing fabric, whichis estimated at 163 lbs/100 square yards versus the new liner which is113 lbs/100 square yards. This reduction is approximately 50 lbs reducedweight for 100 square yards (approximately the amount of material tocover the airframe of a cargo aircraft such as a Chinook), which isapproximately a 30% drop in weight per aircraft from the prior art linerto the liner of the present invention.

Also important is the weight difference between prior art liners and theliner of the present invention once the liner has been installed for aperiod of time. The liner of the present invention eliminates weightgain while the liner is in use (due to the accumulation of water,moisture, oil/fuel and other contaminates into the liner) and preferablyobtains a maximum gain of 5% weight once saturated/aged. In thepreferred embodiment, the laminated, multi-layer liner is treated with acontinuous gas plasma process utilizing nano fluorocarbons, assuringpenetrations through all 5 layers of the laminated multi-layer linersuch that the multi-layer liner absorbs less than 5% of the dry weightwhen tested by a 1 minute soak in water on both facing and backinglayers followed by a 5 minute drip dry. Further, the nano fluorocarbontreatment will render the multi-layer liner resistant to mold and mildewgrowth as tested by MIL-STD-810G, Method 508.6, 84 day exposure. Priorart liners gain significant over time weight from water, oils and othercontaminants. Existing liners can gain 50% of their original weight,causing a 163 lb liner to weigh 245 lbs over time. The combination ofthe layers and assembly method used in the liner of the presentinvention is such that the liner does not absorb the water, oils andcontaminants as occurs with prior art liners. Since the liner of thepresent invention does not absorb water, oils and contaminants, theliner has been shown to exhibit only a 5% gain in weight over the sametime period as the prior art liners, resulting in a liner that weighsapproximately 124 lbs. This has been shown in actual use of anoperational U.S. Army CH-47F Chinook helicopter as well as in labtesting by weighing the liner in a conditioned environment followed by a1 minute soak on each face in water before a 5 minute drip dry todetermine the saturated weight.

Although the multi-layer liner is described in terms of use in aircraft,as a liner, it is contemplated and within the scope of the presentinvention that the liner could be used for many other purposes. Forexample, the multi-layer liner could be used in watercraft, automobiles,military vehicles, or anywhere where traditional liners suffer from theperformance issues outlined above.

The present invention creates a multi-layered liner material thataddresses all of the problems encountered in the prior art. The liner ofthe present invention reduces the initial weight and weight over time ofthe liner, the liner reduces corrosion to the air frame by preventingmoisture build up behind the liner (see FIG. 3), the liner increasethermal and acoustical performance, and the process of creating theliner through lamination creates a product that is superior and easierto fix that the prior art. The liner of the present invention preferablyhas a five year design life, is field repairable, is resistant to moldand mildew, is fire-resistant and is also ESD rated. The multi-layerliner exhibits a smoke specific optical density of less than 200 whentested to FAR 25.853 appendix F part V and combustion toxicity is lessthan 25% of the maximum allowable values according to BSS 7239. Further,the material shall pass these tests without the use of any brominated orTris flame retardants.

Modifications and substitutions by one of ordinary skill in the art areconsidered to be within the scope of the present invention, which is notto be limited except by the allowed claims and their legal equivalents.

The invention claimed is:
 1. A multi-layer, light weight and highlybreathable/air permeable thermal/acoustical liner, said multi-layerliner comprising: a nonwoven, fire resistant (FR), air permeable,hydrophobic and oleophobic thermal and acoustical insulation core layerhaving an upper surface and a lower surface, said insulation core layerinherently fire resistant with no chemical treatment providing soundtransmission loss of; at least 10 dB in the 250 to 1,000 Hz range, and20 dB in the 1,000 to 10,000 Hz ranges; and an insulation R value of 1.8or greater; a first highly breathable, hydrophobic and oleophobic layerdisposed proximate and adjacent said upper surface of said insulationcore layer, said first highly breathable layer constructed from an ePTFEmembrane, said first highly breathable, hydrophobic and oleophobic layeris hydrophobic to a level of at least 10 m water column; a second highlybreathable, hydrophobic and oleophobic layer disposed proximate andadjacent said lower surface of said insulation core layer, said secondhighly breathable, hydrophobic and oleophobic layer hydrophobic to alevel of at least 10 m water column; a facing layer disposed proximateand adjacent a surface of said first highly breathable layer that isopposite a surface that is proximate and adjacent said insulation corelayer, wherein said facing is constructed from a material that is highlybreathable and fire-resistant, said facing layer comprised of a hybridof fire-resistant combination of rayon, nylon and aramid/para-aramidconfigured to provide inherent fire resistance with no chemicaltreatment; and a backing layer disposed proximate and adjacent a surfaceof said second highly breathable layer that is opposite a surface thatis proximate and adjacent said insulation core layer, wherein saidbacking is a highly breathable, fire-resistant material, said backinglayer comprised of a hybrid of fire-resistant combination of rayon,nylon and aramid/para-aramid configured to provide inherent fireresistance with no chemical treatment, and wherein said insulation core,said first highly breathable layer, said second highly breathable layer,said facing and said backing layers of said multi-layer liner arelaminated to one another, and wherein said laminated multi-layer linerexhibits air permeability to 0.10 CFM and MVTR of 3500 g/m²/24 hr highlybreathable once laminated together.
 2. The multi-layer liner accordingto claim 1, wherein said acoustical insulation core layer has a densityof equal to or less than 0.60 pounds per cubic foot and a thermalconductivity of greater than or equal to 0.24 (Btu·In.)/(Sq.Ft·Hr° F.).3. The multi-layer liner according to claim 2, wherein said insulationcore layer is a foam layer.
 4. The multi-layer liner according to claim3, wherein said foam layer is a hydrophobic melamine foam layer.
 5. Themulti-layer liner according to claim 3, wherein said foam layer isconfigured for passing Federal Aviation Administration flammability,smoke generation, and combustion toxicity requirements.
 6. Themulti-layer liner according to claim 1, wherein said acousticalinsulation core layer has a density of equal to or less than 0.40 poundsper cubic foot and a thermal conductivity of greater than or equal to0.34 (Btu·In.)/(Sq.Ft·Hr° F.).
 7. The multi-layer liner according toclaim 1, wherein said first highly breathable layer and said secondhighly breathable layers exhibit air permeability to 0.10 CFM and MVTRof 3500 g/m²/24 hr and are inherently fire resistant.
 8. The multi-layerliner according to claim 1, wherein said first and second highlybreathable layers are resistant to oil and hydrophobic to a level of atleast 10 m water column, protecting the thermal and acousticalinsulation layer from contamination by fluids and particulates, down to0.3 microns, which could lead to weight gain and further performancedegradation.
 9. The multi-layer liner according to claim 1 wherein themulti-layer liner is not treated with any brominated or Tris flameretardants and wherein said multi-layer liner exhibits a smoke specificoptical density of less than 200 when tested to FAR 25.853 appendix Fpart V and a combustion toxicity of less than 25% of the maximumallowable values according to BSS
 7239. 10. The multi-layer lineraccording to claim 1, wherein said laminated, multi-layer liner istreated with a continuous gas plasma process utilizing nanofluorocarbons, assuring penetrations through all 5 layers of thelaminated multi-layer liner such that the multi-layer liner absorbs lessthan 5% of the dry weight when tested by a 1 minute soak in water onboth facing and backing layers followed by a 5 minute drip dry. Further,the nano fluorocarbon treatment will render the multi-layer linerresistant to mold and mildew growth as tested by MIL-STD-810G, Method508.6, 84 day exposure.
 11. The multi-layer liner according to claim 1,wherein said nonwoven, fire resistant (FR), air permeable, hydrophobicand oleophobic thermal and acoustical insulation core is constructed atleast in part from one or more materials selected from the group ofmaterials consisting of a non-woven, amorphous thermoplasticpolyetherimide (PEI) resin material or an amorphous polysilicic aciddrawn from SiO2 material or oxidized polyacrylonitrile or similar thatare able to pass vibrational integrity testing MIL-STD-810G method514.6, Procedure I without needing quilting or other means forpreventing fiber migration.
 12. The multi-layer liner according to claim1, wherein said multi-layer liner includes means for providingelectro-static discharge (ESD) performance characteristics in the rangeof 1-100 MOhm when tested with 500 volts potential as per DIN testmethod 54345 or at most a 0.2 second discharge time for 5000 volt chargewhen applied to either the facing or backing as per FED 191A method5931.
 13. The multi-layer liner according to claim 7, wherein said meansfor providing electro-static discharge (ESD) performance characteristicsto said multi-layer liner includes providing both of said first andsecond highly breathable layers with a carbon impregnated ePTFEmaterial.
 14. The multi-layer liner according to claim 7, wherein saidmeans for providing electro-static discharge (ESD) performancecharacteristics to said multi-layer liner includes providing both ofsaid first and second highly breathable layers with a carbon printingpattern on at least an interior surface of said first and second highlybreathable layers.
 15. The multi-layer liner according to claim 9,wherein said means for providing electro-static discharge (ESD)performance characteristics to said multi-layer liner includes providingboth of said facing layer and said backing layer with a carbon printingpattern on an interior surface of at least one of the facing layer andthe backing layer, and wherein said interior surface of said facinglayer including said carbon printing pattern is located on a surface ofthe facing layer that contacts the first highly breathable layer, andwherein said interior surface of the backing layer that contacts thesecond highly breathable layer is located on a surface of the backinglayer that contacts the second highly breathable layer.
 16. Amulti-layer, light weight and highly breathable/air permeablethermal/acoustical liner, said multi-layer liner comprising: a nonwoven,fire resistant (FR), air permeable, hydrophobic and oleophobic thermaland acoustical insulation core layer having an upper surface and a lowersurface, said insulation core layer inherently flame resistant with nochemical treatment and hydrophobic, wherein said acoustical insulationcore layer has a density of equal to or less than 0.60 pounds per cubicfoot and a thermal conductivity of greater than or equal to 0.24(Btu·In.)/(Sq.Ft·Hr° F.); a first highly breathable, hydrophobic andoleophobic layer disposed proximate and adjacent said upper surface ofsaid insulation core layer, said first highly breathable layerconstructed from an ePTFE membrane, said first highly breathable,hydrophobic and oleophobic layer is hydrophobic to a level of at least10 m water column; a second highly breathable, hydrophobic andoleophobic layer disposed proximate and adjacent said lower surface ofsaid insulation core layer, said second highly breathable layerconstructed from an ePTFE membrane said second highly breathable,hydrophobic and oleophobic layer hydrophobic to a level of at least 10 mwater column; a facing layer disposed proximate and adjacent a surfaceof said first highly breathable layer that is opposite a surface that isproximate and adjacent said insulation core layer, wherein said facingis constructed from a material that is highly breathable andfire-resistant, said facing layer comprised of a hybrid offire-resistant rayon, nylon and a para-aramid synthetic fiber configuredto provide inherent fire resistance with no chemical treatment, andwherein said facing layer is hydrophobic; and a backing layer disposedproximate and adjacent a surface of said second highly breathable layerthat is opposite a surface that is proximate and adjacent saidinsulation core layer, wherein said backing is a highly breathable,fire-resistant material, said backing layer comprised of a hybrid offire-resistant rayon, nylon and Kevlar configured to provide inherentfire resistance with no chemical treatment, and wherein said backinglayer is hydrophobic t, and wherein said insulation core, said firsthighly breathable layer, said second highly breathable layer, saidfacing and said backing layers of said multi-layer liner are laminatedto one another, and wherein said laminated multi-layer liner exhibits.17. The multi-layer liner according to claim 16, wherein said firsthighly breathable layer, said second highly breathable layer, saidfacing layer, said backing layer and said core exhibit air permeabilityto 0.10 CFM and MVTR of 3500 g/24 hr and are inherently fire resistant,said exhibited air permeability including exposed to an elevatedtemperature caused by fire and/or heat.
 18. The multi-layer lineraccording to claim 16, wherein said facing layer is resistant to oil.19. The multi-layer liner according to claim 16, wherein said facinglayer is constructed from a fabric comprising a hybrid of inherentlyfire resistant rayon, nylon and a para-aramid synthetic fiber.
 20. Themulti-layer liner according to claim 16, wherein at least one of saidfacing layer and said backing layer is treated with a nanoscopiccoating.
 21. The multi-layer liner according to claim 16, wherein saidnonwoven, fire resistant (FR), air permeable, hydrophobic and oleophobicthermal and acoustical insulation core is constructed at least in partfrom one or more materials selected from the group of materialsconsisting of a non-woven, amorphous thermoplastic polyetherimide (PEI)resin material and an amorphous polysilicic acid drawn from SiO2material.
 22. The multi-layer liner according to claim 16, wherein saidinsulation core is fabricated from one or more materials selected fromthe group of materials consisting of a non-woven, amorphousthermoplastic polyetherimide (PEI) resin material, an amorphouspolysilicic acid drawn from SiO2 material, and aramid fiber.
 23. Themulti-layer liner according to claim 16, wherein said multi-layer linerincludes means for providing electro-static discharge (ESD) performancecharacteristics to said multi-layer liner.
 24. The multi-layer lineraccording to claim 23, wherein said means for providing electro-staticdischarge (ESD) performance characteristics to said multi-layer linerincludes providing both of said first and second highly breathablelayers with a carbon impregnated ePTFE material.
 25. The multi-layerliner according to claim 23, wherein said means for providingelectro-static discharge (ESD) performance characteristics to saidmulti-layer liner includes providing at least one of said facing layerand said backing layer with a carbon printing pattern on at least aninterior surface of one of said facing and backing layers.
 26. Themulti-layer liner according to claim 23, wherein said means forproviding electro-static discharge (ESD) performance characteristics tosaid multi-layer liner includes providing both of said facing layer andsaid backing layer with a carbon printing pattern on an interior surfaceof at least one of the facing layer and the backing layer, and whereinsaid interior surface of said facing layer including said carbonprinting pattern is located on a surface of the facing layer thatcontacts the first highly breathable layer, and wherein said interiorsurface of the backing layer that contacts the second highly breathablelayer is located on a surface of the backing layer that contacts thesecond highly breathable layer.
 27. The multi-layer liner according toclaim 23, wherein said multi-layer liner provides ESD performancecharacteristics in the range of 1-100 MOhm when tested with 500 voltspotential as per DIN test method 54345 or at least a 0.5 seconddischarge time for 5000 volt charge both facing and backing as per FED191A method
 5931. 28. A multi-layer, light weight and highlybreathable/air permeable thermal/acoustical liner, said multi-layerliner comprising: a nonwoven, fire resistant (FR), air permeable,hydrophobic and oleophobic thermal and acoustical insulation melaminefoam core layer having an upper surface and a lower surface, saidinsulation melamine foam core layer inherently fire resistant with nochemical treatment providing sound transmission loss of; at least 10 dBin the 250 to 1,000 Hz range, and 20 dB in the 1,000 to 10,000 Hzranges; and an insulation R value of 3.5 or greater, and a density ofequal to or less than 0.60 pounds per cubic foot and a thermalconductivity of greater than or equal to 0.24 (Btu·In.)/(Sq.Ft·Hr° F.),and configured for passing Federal Aviation Administration flammability,smoke generation, and combustion toxicity requirements; a first highlybreathable, hydrophobic and oleophobic layer disposed proximate andadjacent said upper surface of said insulation melamine foam core layer,said first highly breathable layer constructed from an ePTFE membrane,said first highly breathable, hydrophobic and oleophobic layer ishydrophobic to a level of at least 10 m water column; a second highlybreathable, hydrophobic and oleophobic layer disposed proximate andadjacent said lower surface of said insulation melamine foam core layer,said second highly breathable, hydrophobic and oleophobic layerhydrophobic to a level of at least 10 m water column; a facing layerdisposed proximate and adjacent a surface of said first highlybreathable layer that is opposite a surface that is proximate andadjacent said insulation melamine foam core layer, wherein said facingis constructed from a material that is highly breathable andfire-resistant, said facing layer comprised of a hybrid offire-resistant combination of rayon, nylon and aramid/para-aramidconfigured to provide inherent fire resistance with no chemicaltreatment; and a backing layer disposed proximate and adjacent a surfaceof said second highly breathable layer that is opposite a surface thatis proximate and adjacent said insulation melamine foam core layer,wherein said backing is a highly breathable, fire-resistant material,said backing layer comprised of a hybrid of fire-resistant combinationof rayon, nylon and aramid/para-aramid configured to provide inherentfire resistance with no chemical treatment, and wherein said insulationmelamine foam core, said first highly breathable layer, said secondhighly breathable layer, said facing and said backing layers of saidmulti-layer liner are laminated to one another, and wherein saidlaminated multi-layer liner exhibits air permeability to 0.10 CFM andMVTR of 3500 g/m²/24 hr highly breathable once laminated together. 29.The multi-layer, light weight and highly breathable/air permeablethermal/acoustical liner of claim 28, wherein said insulation melaminefoam core layer has a density of equal to or less than 0.40 pounds percubic foot and a thermal conductivity of greater than or equal to 0.34(Btu·In.)/(Sq.Ft·Hr° F.).